In recent years, mobile satellite communications has been developing for commercial use. However, telephone charges in satellite communications are generally expensive, and power consumption is far greater as compared to that in a mobile terminal providing services from a ground station. Accordingly, a user usually uses services in a ground system as much as possible in an area where the ground system can be used, and uses a satellite system in an area where the ground system can not be used. In the system described above, it is desirable that services in the satellite system and those in the ground system are utilized with one terminal unit from view points of reduction in a required number of terminals as well as of user's convenience.
FIG. 10 is a block diagram showing a relation between a plurality of radio communication services and multiple services radio communication device in a communication system based on the conventional technology and showing the radio communication device for the same. In the figure, designated at reference numeral 1 is a cellular service radio communication device, at 2 a satellite service radio communication device, at 3 a multiple services radio communication device including therein the cellular service communication device 1 and the satellite service communication device 2. The reference numeral 1a indicates a service A communication control section provided in the cellular service radio communication device 1 and for catching lines for service A and controlling communications, and the reference numeral 2a indicates a service B communication control section provided in the satellite service radio communication device 2 and for catching lines for service B and controlling communications. Herein, the service A corresponds to the cellular service, while the service B corresponds to the satellite service.
The reference numeral 4 indicates a base station of the communication system interfacing to radio communication services for providing services, for example services A and B, to the multiple services radio communication device 3. The reference numerals 5a, 5b indicate a transmission path for position registration signals comprising analog signals or digital signals to the radio communication services A and B respectively. The reference numerals 1b, 2b indicate a transmission path for signals indicating a situation for catching receiving lines for each of services from the services A, B communication control sections respectively. The reference numeral 1c, 2c indicate a transmission path for signals indicating services each provided to a user respectively. The reference numeral 6 indicates multiple services switching communication control section. The reference numeral 6a indicates a transmission path for a signal indicating which of the services is being provided to a user, and the reference numeral 6b indicates a transmission path for a signal indicating contents of a service selected by and transmitted from a user.
Next description is made for an operation for switching services provided to a user and a position registering operation in the multiple services radio communication device.
Signals 1b, 2b each indicating a situation of catching receiving lines for services A and B respectively are transmitted from the service A communication control section 1a and service B communication control section 2a to the multiple services switching communication control section 6. The multiple services switching communication control section 6 receives these signals 1b, 2b, and analyzes and determines which of the services from the service A and service B should be provided to a user.
Then the multiple services switching communication control section 6 outputs signals 1c, 2c each indicating a new service provided to a user as a result of analysis of the signals respectively to the service A communication control section 1a as well as to the service B communication control section 2a. The service A communication control section 1a and the service B communication control section 2a understand which of the services is to be provided to the user by receiving the result, and as a result, the communication control section 1a or 2a which is to control a service to be provided anew executes position registration. Furthermore the multiple services switching communication control section 6 informs the user of the service which has been selected with the signal 6a.
The multiple services switching communication control section 6 switches the service to one to be provided to the user, in response to the request 6b from the user, by outputting the signals 1c, 2c indicating the service, and can execute position registration for the communication control section 1a or 2a for controlling the selected new service.
As described above, in the radio communication system based on the conventional technology, each time when a service to be provided to a user is changed, position registration for a base station for the next new service has to be executed.
Next, description is made for a mechanism of generation of unnecessary position registration between the base station and a terminal in the radio communication system based on the conventional technology.
FIGS. 11A to 11C are views showing a sequence of position registration in the radio communication system based on the conventional technology. FIG. 11A shows a state 1, FIG. 11B shows a state 2, and FIG. 11C shows a state 3 respectively.
At first, description is made for the state 1 with reference to FIG. 11A. The multiple services radio communication device 3, which is a terminal, catches a line for the service A, and executes position registration therefor. On the other hand, the multiple services radio communication device 3 does not execute position registration for the service B.
In this step, the service A in the side of base station recognizes that the position of this terminal has been registered under the service A. The multiple services radio communication device 3, which is a side of terminal, also recognizes that the position registration for the service A is completed.
Next description is made for the state 2 with reference to FIG. 11B. In the state 2, it is assumed that a service provided to a user is automatically or manually switched from the service A to the service B. However, in a case where position registration for the service B is failed for some reasons or other, the service B, which is the side of base station, recognizes that position registration of the terminal, i.e. of the communication system device 3, has not been executed under the service. On the other hand, the service A still has recognition that the position registration has continuously been kept under the service.
Furthermore, description is made for the state 3 with reference to FIG. 11C. In the state 3, it is assumed that a service provided to a user is automatically or manually returned to the service A. In this step, in the position registration control based on the conventional technology, a position is registered again to the service A. However, execution of the position registration at the second time is not required because the service A, which is the side of base station, still has kept the recognition that the position registration for the terminal has been completed even if the position registration has not been executed in this step.
As described above, by executing position registration each time when a service provided to a user is changed, an unnecessary control of position registration for the base station is generated, and the terminal side executes position registration which is unnecessary for the side of base station.
Next, FIG. 12 shows an interface for position registration. Herein, description is made for generation of unnecessary position registration between the station and a terminal.
As shown in FIG. 12, a position registration interface is executed with signals only for a request from the terminal side as well as for a response from the side of base station.
Description is made for normal operations according to FIG. 12. At first, a registration request for requiring position registration is transmitted from a terminal, device 3, to the base station. The base station receives, device 4 the registration request, and transmits a registration response to the terminal. At this time, the base station recognizes that the position registration is completed. The terminal side also receives the registration response, and recognizes that the position registration is completed.
Next, a case wherein the base station transmits a response to the registration request to the terminal but the terminal can not receive the response due to some external reasons is assumed. In this case, the base station recognizes that the position registration has been completed. The terminal side recognizes that the position registration has been failed. For this reason, the terminal side executes position registration again which is unnecessary for the base station.
Accordingly, by executing again the position registration each time when position registration is failed, unnecessary control for position registration for the base station is generated as described above, and the terminal side executes position registration which is unnecessary for the base station.
It should be noted that the technological background in relation to the present invention is disclosed in Japanese Patent Laid-Open Publication No. HEI 4-351127, and Japanese Patent Laid-Open Publication No. HEI 6-506818.
In the radio communication devices communicating with a plurality of terminals based on the conventional technology, as described above, position registration has to be executed each time when a service provided to a user is changed or when position registration is failed. For this reason, there have been generated some problems such as generation of a control for position registration and an output for transmission, which are unnecessary to the base station which is a new service as a destination for radio communications, for instance, when power to the multiple services radio communication device is turned ON, when a service to be provided is automatically and manually changed, and when position registration is failed.
In addition, there has been a problem that because the unnecessary position registration request is transmitted from the radio communication device, the base station has to execute processing for the position registration corresponding thereto which also causes the base station to be highly loaded in response thereto.
Furthermore, there has been a problem that a transmission request such as a outgoing call request which is a request from a user is refused because a transmitting/receiving control section is controlling for transmission of position registration while unnecessary transmission thereof is executed in the radio communication device.